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D-xylopyranosyl-substituted phenyl derivatives, medicaments containing such compounds, their use and process for their manufacture |
| 7393836 |
D-xylopyranosyl-substituted phenyl derivatives, medicaments containing such compounds, their use and process for their manufacture
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| Patent Drawings: | |
| Inventor: |
Eckhardt, et al. |
| Date Issued: |
July 1, 2008 |
| Application: |
11/168,905 |
| Filed: |
June 28, 2005 |
| Inventors: |
Eckhardt; Matthias (Biberach, DE)
Himmelsbach; Frank (Mittelbiberach, DE)
Eickelmann; Peter (Mittelbiberach, DE)
Thomas; Leo (Biberach, DE)
Barsoumian; Edward Leon (Toyonaka, JP)
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| Assignee: |
Boehringer Ingelheim International GmbH (Ingelheim, DE) |
| Primary Examiner: |
Jiang; Shaojia Anna |
| Assistant Examiner: |
McIntosh, III; Traviss C. |
| Attorney Or Agent: |
Dow; David A.Morris; Michael P.Devlin; Mary-Ellen M. |
| U.S. Class: |
514/23; 536/1.11 |
| Field Of Search: |
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| International Class: |
A01N 43/04; A61K 31/70; C07H 1/00 |
| U.S Patent Documents: |
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| Foreign Patent Documents: |
WO 98/31697; WO 01/27128; WO 02/083066; WO 03/099836; WO 2004/013118; WO 2004/052902; WO 2004/052903; WO 2004/080990; WO 2005/012326 |
| Other References: |
Adachi et al., "T-1095, a Renal Na+-Glucose Transport Inhibitor", Metabolism, vol. 49 (8), 2000, 990-995. cited by examiner. |
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| Abstract: |
A D-Xylopyranosyl-substituted phenyl compound of general formula I ##STR00001## wherein the groups R.sup.1 to R.sup.5, X, Z and R.sup.7a, R.sup.7b, R.sup.7c are defined as in claim 1, have an inhibiting effect on the sodium-dependent glucose cotransporter SGLT. The present invention also relates to pharmaceutical compositions for the treatment of metabolic disorders. |
| Claim: |
The invention claimed is:
1. A D-Xylopyranosyl-substituted phenyl compound of formula I ##STR00084## wherein R.sup.1 denotes hydrogen, fluorine, chlorine, bromine, C.sub.1-6-alkyl,C.sub.2-6-alkynyl, C.sub.2-6-alkenyl, C.sub.3-7-cycloalkyl, C.sub.3-7-cycloalkyl-C.sub.1-3-alkyl, C.sub.5-7-cycloalkenyl, C.sub.5-7-cycloalkenyl-C.sub.1-3-alkyl, C.sub.1-4-alkylcarbonyl, arylcarbonyl, heteroarylcarbonyl, aminocarbonyl,C.sub.1-4-alkylaminocarbonyl, di-(C.sub.1-3-alkyl)aminocarbonyl, pyrrolidin-1-ylcarbonyl, piperidin-1-ylcarbonyl, morpholin-4-ylcarbonyl, piperazin-1-ylcarbonyl, 4-(C.sub.1-4-alkyl)piperazin-1-ylcarbonyl, C.sub.1-4-alkoxycarbonyl, amino,C.sub.1-4-alkylamino, di-(C.sub.1-3-alkyl)amino, pyrrolidin-1-yl, piperidin-1-yl, morpholin-4-yl, piperazin-1-yl, 4-(C.sub.1-4-alkyl)piperazin-1-yl, C.sub.1-4-alkylcarbonylamino, C.sub.1-6-alkyloxy, C.sub.3-7-cycloalkyloxy, C.sub.5-7-cycloalkenyloxy,aryloxy, C.sub.1-4-alkylsulphanyl, C.sub.1-4-alkylsulphinyl, C.sub.1-4-alkylsulphonyl, C.sub.3-7-cycloalkylsulphanyl, C.sub.3-7-cycloalkylsulphinyl, C.sub.3-7-cycloalkylsulphonyl, C.sub.5-7-cycloalkenylsulphanyl, C.sub.5-7-cycloalkenylsulphinyl,C.sub.5-7-cycloalkenylsulphonyl, arylsulphanyl, arylsulphinyl, arylsulphonyl, hydroxy, cyano or nitro, while alkyl, alkenyl, alkynyl, cycloalkyl and cycloalkenyl groups may be partly or completely fluorinated or may be mono- or disubstituted by identicalor different substituents selected from chlorine, hydroxy, C.sub.1-3-alkoxy and C.sub.1-3-alkyl, and in cycloalkyl and cycloalkenyl groups one or two methylene groups may be replaced independently of one another by O, S, CO, SO or SO.sub.2, and inN-heterocycloalkyl groups a methylene group may be replaced by CO or SO.sub.2, and R.sup.2 denotes hydrogen, fluorine, chlorine, bromine, hydroxy, C.sub.1-4-alkyl, C.sub.1-4-alkoxy, cyano or nitro, while alkyl groups may be mono- or polysubstituted byfluorine, or in the event that R.sup.1 and R.sup.2 are bound to two C atoms of the phenyl ring which are adjacent to one another, R.sup.1 and R.sup.2 may be joined together in such a way that R.sup.1 and R.sup.2 together form a C.sub.3-5-alkylene orC.sub.3-5-alkenylene bridge, which may be partly or totally fluorinated or mono- or disubstituted by identical or different substituents selected from chlorine, hydroxy, C.sub.1-3-alkoxy and C.sub.1-3-alkyl and wherein one or two methylene groups may bereplaced independently of one another by O, S, CO, SO, SO.sub.2 or NR.sup.N, R.sup.3 denotes hydrogen, fluorine, chlorine, bromine, C.sub.1-6-alkyl, C.sub.2-6-alkynyl, C.sub.2-6-alkenyl, C.sub.3-7-cycloalkyl, C.sub.3-7-cycloalkyl-C.sub.1-3-alkyl,C.sub.5-7-cycloalkenyl, C.sub.5-7-cycloalkenyl-C.sub.1-3-alkyl, aryl, heteroaryl, C.sub.1-4-alkylcarbonyl, arylcarbonyl, heteroarylcarbonyl, aminocarbonyl, C.sub.1-4-alkylaminocarbonyl, di-(C.sub.1-3-alkyl)aminocarbonyl, pyrrolidin-1-ylcarbonyl,piperidin-1-ylcarbonyl, morpholin-4-ylcarbonyl, piperazin-1-ylcarbonyl, 4-(C.sub.1-4-alkyl)piperazin-1-ylcarbonyl, hydroxycarbonyl, C.sub.1-4-alkoxycarbonyl, C.sub.1-4-alkylamino, di-(C.sub.1-3-alkyl)amino, pyrrolidin-1-yl, piperidin-1-yl,morpholin-4-yl, piperazin-1-yl, 4-(C.sub.1-4-alkyl)piperazin-1-yl, C.sub.1-4-alkylcarbonylamino, arylcarbonylamino, heteroarylcarbonylamino, C.sub.1-4-alkylsulphonylamino, arylsulphonylamino, C.sub.1-6-alkoxy, C.sub.3-7-cycloalkyloxy,C.sub.5-7-cycloalkenyloxy, aryloxy, heteroaryloxy, C.sub.1-4-alkylsulphanyl, C.sub.1-4-alkylsulphinyl, C.sub.1-4-alkylsulphonyl, C.sub.3-7-cycloalkylsulphanyl, C.sub.3-7-cycloalkylsulphinyl, C.sub.3-7-cycloalkylsulphonyl, C.sub.5-7-cycloalkenylsulphanyl,C.sub.5-7-cycloalkenylsulphinyl, C.sub.5-7-cycloalkenylsulphonyl, arylsulphanyl, arylsulphinyl, arylsulphonyl, amino, hydroxy, cyano or nitro, while alkyl, alkenyl, alkynyl, cycloalkyl and cycloalkenyl groups may be partly or totally fluorinated or mono-or disubstituted by identical or different substituents selected from chlorine, hydroxy, C.sub.1-3-alkoxy and C.sub.1-3-alkyl, and in cycloalkyl and cycloalkenyl groups one or two methylene groups may be replaced independently of one another by O, S, CO,SO or SO.sub.2, and in N-heterocycloalkyl groups a methylene group may be replaced by CO or SO.sub.2, and R.sup.4 denotes hydrogen, fluorine, chlorine, bromine, iodine, cyano, nitro, C.sub.1-3-alkyl, C.sub.1-3-alkoxy or methyl or methoxy substituted by 1to 3 fluorine atoms, or in the event that R.sup.3 and R.sup.4 are bound to two C atoms of the phenyl ring which are adjacent to one another, R.sup.3 and R.sup.4 may be joined together in such a way that R.sup.3 and R.sup.4 together form aC.sub.3-5-alkylene or C.sub.3-5-alkenylene bridge, which may be partly or totally fluorinated or mono- or disubstituted by identical or different substituents selected from chlorine, hydroxy, C.sub.1-3-alkoxy and C.sub.1-3-alkyl and wherein one or twomethylene groups may be replaced independently of one another by O, S, CO, SO, SO.sub.2 or NR.sup.N, R.sup.5 denotes hydrogen, fluorine, chlorine, bromine, iodine, cyano, nitro, C.sub.1-3-alkyl, C.sub.1-3-alkoxy or methyl or methoxy substituted by 1 to 3fluorine atoms, and R.sup.N independently of one another denote H or C.sub.1-4-alkyl, L are selected independently of one another from among fluorine, chlorine, bromine, iodine, C.sub.1-3-alkyl, difluoromethyl, trifluoromethyl, C.sub.1-3-alkoxy,difluoromethoxy, trifluoromethoxy and cyano, R.sup.7a, R.sup.7b, and R.sup.7c independently of one another have a meaning selected from among hydrogen, (C.sub.1-18-alkyl)carbonyl, (C.sub.1-18-alkyl)oxycarbonyl, arylcarbonyl andaryl-(C.sub.1-3-alkyl)-carbonyl, X denotes hydrogen, C.sub.1-6-alkyl, C.sub.2-6-alkynyl, C.sub.2-6-alkenyl, C.sub.3-7-cycloalkyl, C.sub.3-7-cycloalkyl-C.sub.1-3-alkyl, C.sub.5-7-cycloalkenyl, C.sub.5-7-cycloalkenyl-C.sub.1-3-alkyl, aryl,aryl-C.sub.1-3-alkyl, heteroaryl, heteroaryl-C.sub.1-3-alkyl, C.sub.1-4-alkylcarbonyl, arylcarbonyl, aminocarbonyl, C.sub.1-4-alkylaminocarbonyl, di-(C.sub.1-3-alkyl)aminocarbonyl, (aryl-C.sub.1-3-alkyl)aminocarbonyl, pyrrolidin-1-ylcarbonyl,piperidin-1-ylcarbonyl, morpholin-4-ylcarbonyl, hydroxycarbonyl, C.sub.1-4-alkoxycarbonyl, C.sub.1-4-alkylcarbonylamino-C.sub.1-3-alkyl, N-(C.sub.1-4-alkylcarbonyl)-N-(C.sub.1-3-alkyl)-amino-C.sub.1-3-alkyl, arylcarbonylamino-C.sub.1-3-alkyl,C.sub.1-4-alkylsulphonylamino-C.sub.1-3-alkyl, arylsulphonylamino-C.sub.1-3-alkyl, C.sub.1-6-alkoxy-C.sub.1-3-alkyl, C.sub.3-7-cycloalkyloxy-C.sub.1-3-alkyl, C.sub.5-7-cycloalkenyloxy-C.sub.1-3-alkyl, aryloxy-C.sub.1-3-alkyl, heteroaryloxy-C.sub.1-3-alkyl, C.sub.1-4-alkylsulphanyl-C.sub.1-3-alkyl, C.sub.1-4-alkylsulphinyl-C.sub.1-3-alkyl, C.sub.1-4-alkylsulphinyl, C.sub.1-4-alkylsulphonyl, C.sub.1-4-alkylsulphonyl-C.sub.1-3-alkyl, C.sub.1-4-arylsulphanyl-C.sub.1-3-alkyl,arylsulphonyl-C.sub.1-3-alkyl, aryl-C.sub.1-3-alkyl-sulphonyl-C.sub.1-3-alkyl, C.sub.1-4-alkylsulphonyloxy-C.sub.1-3-alkyl, arylsulphonyloxy-C.sub.1-3-alkyl, aryl-C.sub.1-3-alkyl-sulphonyloxy-C.sub.1-3-alkyl,C.sub.3-7-cycloalkylsulphanyl-C.sub.1-3-alkyl, C.sub.3-7-cycloalkylsulphinyl, C.sub.3-7-cycloalkylsulphonyl, C.sub.5-7-cycloalkenylsulphanyl-C.sub.1-3-alkyl, C.sub.5-7-cycloalkenylsulphinyl, C.sub.5-7-cycloalkenylsulphonyl,C.sub.1-4-alkylcarbonylsulphanyl-C.sub.1-3-alkyl or cyano, while alkyl, alkenyl, alkynyl, cycloalkyl and cycloalkenyl groups may be partly or totally fluorinated or mono- or disubstituted by identical or different substituents selected from chlorine,cyano, hydroxy, mercapto, C.sub.1-3-alkoxy and C.sub.1-3-alkyl, and in cycloalkyl and cycloalkenyl groups one or two methylene groups may be replaced independently of one another by O, S, CO, SO or SO.sub.2, and in N-heterocycloalkyl groups a methylenegroup may be replaced by CO or SO.sub.2, and provided that X representing hydroxymethyl is excluded, Z denotes oxygen, methylene, dimethylmethylene, difluoromethylene or carbonyl; while the term aryl groups used in the definition of the above groupsdenotes phenyl or naphthyl groups, which may be mono- or disubstituted independently of one another by identical or different groups L; and the term heteroaryl groups used in the definition of the above-mentioned groups denotes a pyrrolyl, furanyl,thienyl, pyridyl, indolyl, benzofuranyl, benzothiophenyl, quinolinyl or isoquinolinyl group, or a pyrrolyl, furanyl, thienyl, pyridyl or imidazolyl group, wherein one or two methyne groups are replaced by nitrogen atoms, or an indolyl, benzofuranyl,benzothiophenyl, quinolinyl or isoquinolinyl group, wherein one to three methyne groups are replaced by nitrogen atoms, while the above-mentioned heteroaryl groups may be mono- or disubstituted independently of one another by identical or differentgroups L; while by the N-heterocycloalkyl group mentioned in the definition of the above-mentioned groups is meant a saturated carbocyclic ring which comprises an imino group in the ring, which may comprise another optionally substituted imino group oran O or S atom in the ring, and unless otherwise stated the above-mentioned alkyl groups may be straight-chain or branched, or a tautomer or stereoisomer thereof or mixtures thereof or a salt thereof.
2. A D-Xylopyranosyl-substituted phenyl compound according to claim 1, of formula I.2 ##STR00085## wherein R.sup.1 to R.sup.5, X, Z, R.sup.7a, R.sup.7b, R.sup.7c have the meanings according to claim 1.
3. A D-Xylopyranosyl-substituted phenyl compound according to claim 1, of formula I.2c ##STR00086## wherein R.sup.1 to R.sup.5, X, Z, R.sup.7a, R.sup.7b, R.sup.7c have the meanings according to claim 1.
4. A D-Xylopyranosyl-substituted phenyl compound according to claim 1, wherein R.sup.1 denotes hydrogen, fluorine, chlorine, bromine, C.sub.1-6-alkyl, C.sub.2-6-alkynyl, C.sub.2-6-alkenyl, C.sub.3-7-cycloalkyl, C.sub.5-7-cycloalkenyl,C.sub.1-6-alkyloxy, C.sub.3-7-cycloalkyloxy or cyano, while in cycloalkyl and cycloalkenyl groups one or two methylene units optionally replaced independently of one another by O or CO and alkyl, alkenyl and alkynyl groups may be partly or totallyfluorinated.
5. A D-Xylopyranosyl-substituted phenyl compound according to claim 1 wherein R.sup.3 denotes C.sub.1-6-alkyl, C.sub.2-6-alkynyl, C.sub.1-4-alkyloxy, C.sub.3-7-cycloalkyl, C.sub.3-7-cycloalkyloxy or hydroxy, while in said cycloalkyl groups oneor two methylene units may be replaced independently of one another by O or CO and said alkyl groups may be partly or totally fluorinated.
6. A D-Xylopyranosyl-substituted phenyl compound according to claim 1, wherein X denotes hydrogen, cyano, C.sub.1-6-alkyl, C.sub.2-6-alkynyl, C.sub.2-6-alkenyl, C.sub.1-4-alkylcarbonyl, C.sub.1-4-alkoxycarbonyl, aminocarbonyl,C.sub.1-4-alkylaminocarbonyl, di-(C.sub.1-4-alkyl)aminocarbonyl or C.sub.1-4-alkylcarbonylamino-C.sub.1-3-alkyl, while alkyl groups may be mono- or polyfluorinated or monosubstituted by chlorine or cyano and when X denotes alkyl with 2 or more C atoms,it may be substituted by a hydroxy substituent.
7. A D-Xylopyranosyl-substituted phenyl compound according to claim 1, wherein X denotes C.sub.1-4-alkyloxymethyl, C.sub.3-7-cycloalkyloxymethyl or aryloxymethyl, while by the aryl group is meant a phenyl or naphthyl group, which may be mono-or disubstituted by identical or different groups L and L is defined according to claim 1.
8. A D-Xylopyranosyl-substituted phenyl compound according to claim 1, wherein X denotes mercaptomethyl, C.sub.1-4-alkylsulphanylmethyl or C.sub.1-4-alkylcarbonylsulphanylmethyl.
9. A D-Xylopyranosyl-substituted phenyl compound according to claim 1, wherein X denotes chloromethyl, bromomethyl, iodomethyl, C.sub.1-6-alkylsulphonyloxymethyl, arylsulphonyloxymethyl or aryl-C.sub.1-3-alkyl-sulphonyloxymethyl, while theabove-mentioned alkyl groups may be partly or totally fluorinated or mono- or dichlorinated and the above-mentioned aryl groups may be mono- or disubstituted by identical or different groups L, while L selected from the group consisting of amongfluorine, chlorine, bromine, iodine, C.sub.1-3-alkyl, difluoromethyl, trifluoromethyl and cyano.
10. A D-Xylopyranosyl-substituted phenyl compound according to claim 1, wherein R.sup.2 denotes hydrogen, fluorine, hydroxy, methoxy, ethoxy or methyl.
11. A D-Xylopyranosyl-substituted phenyl compound according to claim 1, wherein R.sup.4 and R.sup.5 independently of one another represent hydrogen or fluorine.
12. A D-Xylopyranosyl-substituted phenyl compound according to claim 1, wherein Z denotes oxygen or methylene.
13. A D-Xylopyranosyl-substituted phenyl compound according to claim 1, wherein R.sup.7a, R.sup.7b, R.sup.7c independently of one another represent hydrogen, (C.sub.1-6-alkyl)oxycarbonyl, (C.sub.1-8-alkyl)carbonyl or benzoyl.
14. A physiologically acceptable salt of a compound according to claim 1 with an inorganic or organic acid.
15. A pharmaceutical composition comprised of a compound according to claim 1 or a physiologically acceptable salt thereof and one or more inert carriers and/or diluents.
16. A pharmaceutical composition according to claim 15 wherein the inert carrier or diluent is incorportated by a nonchemical method.
17. A method of treating a metabolic disorder selected from the group consisting of type 1 or type 2 diabetes mellitus, complications of diabetes, and reactive hypoglycaemia, said method comprised of the step of administering to a patient inneed thereof a therapeutic amount of a pharmaceutical composition comprised of a compound according to claim 1 or a physiologically acceptable salt thereof.
18. A method according to claim 17 wherein the metabolic disorder is type 1 or type 2 diabetes mellitus.
19. A Method of inhibiting the sodium-dependent glucose cotransporter SGLT in a cell by administration of an effective amount of a compound according to claim 1 or a physiologically acceptable salt thereof.
20. A method of reducing the incidence of degeneration of pancreatic beta cells and/or for improving the functionality of pancreatic beta cells, said method comprised of the steps of administering to a patient in need thereof a therapeuticamount of a compound according to claim 1 or a physiologically acceptable salt thereof.
21. A process for preparing a compound formula I according to claim 1 or a tautomer or stereoisomer thereof or mixtures thereof or a salt therof, comprised of the steps of reacting a compound according to formula II: ##STR00087## wherein R'denotes H, C.sub.1-4-alkyl, (C.sub.1-18-alkyl)carbonyl, (C.sub.1-18-alkyl)oxycarbonyl, arylcarbonyl or aryl-(C.sub.1-3-alkyl)carbonyl, wherein the alkyl or aryl groups may be mono- or polysubstituted by halogen; R.sup.8a, R.sup.8b, and R.sup.8cindependently of one another have one of the meanings given for the groups R.sup.7a, R.sup.7b, R.sup.7c, denote a benzyl group or an R.sup.aR.sup.bR.sup.cSi group or a ketal or acetal group, while in each case two adjacent groups R.sup.8a, R.sup.8b,R.sup.8c, and R.sup.8d may form a cyclic ketal or acetal group or a 1,2-di(C.sub.1-3-alkoxy)-1,2-di(C.sub.1-3-alkyl)-ethylene bridge, while the above-mentioned ethylene bridge together with two oxygen atoms and the associated two carbon atoms of thepyranose ring form a substituted dioxane ring, and while alkyl, aryl and/or benzyl groups may be mono- or polysubstituted by halogen or C.sub.1-3-alkoxy and benzyl groups may also be substituted by a di-(C.sub.1-3-alkyl)amino group; and R.sup.a,R.sup.b, R.sup.c independently of one another represent C.sub.1-4-alkyl, aryl or aryl-C.sub.1-3-alkyl, wherein the aryl or alkyl groups may be mono- or polysubstituted by halogen; while the term aryl groups used in the definition of the above groupsdenotes phenyl or naphthyl groups, and X, Z, R.sup.1 to R.sup.5, R.sup.7a, R.sup.7b, and R.sup.7c have the meanings given in claim 1, with a reducing agent in the presence of an acid, and any protective groups present are cleaved at the same time orsubsequently; optionally, cleaving any protective group and/or optionally, selectively derivatizing a compound of formula I at a hydroxy group or substituting a hydroxy group and/or optionally, resolving a compound of formula I thus obtained into itsstereoisomers and/or optionally, converting a compound of formula I thus obtained into a physiologically acceptable salt thereof.
22. A process for preparing a compound of formula I according to claim 1 or a tautomer or stereoisomer therof or mixtures thereof or salt thereof, wherein R.sup.7a, R.sup.7b and R.sup.7c represent hydrogen, said method comprised of the steps ofremoving the groups R.sup.8a, R.sup.8b or R.sup.8c which do not represent hydrogen from a compound of formula III ##STR00088## wherein R.sup.8a, R.sup.8b, and R.sup.8c independently of one another have one of the meanings given for the groups R.sup.7a,R.sup.7b, and R.sup.7c, denote a benzyl group or an R.sup.aR.sup.bR.sup.cSi group or a ketal or acetal group, while in each case two adjacent groups R.sup.8a, R.sup.8b, R.sup.8c, and R.sup.8d may form a cyclic ketal or acetal group or a1,2-di(C.sub.1-3-alkoxy)-1,2-di(C.sub.1-3-alkyl)-ethylene bridge, while the above-mentioned ethylene bridge together with two oxygen atoms and the associated two carbon atoms of the pyranose ring form a substituted dioxane ring, and while alkyl, aryland/or benzyl groups may be mono- or polysubstituted by halogen or C.sub.1-3-alkoxy and benzyl groups may also be substituted by a di-(C.sub.1-3-alkyl)amino group; and wherein at least one of the groups R.sup.8a, R.sup.8b, and R.sup.8c does notrepresent hydrogen; and R.sup.a, R.sup.b, and R.sup.c independently of one another represent C.sub.1-4-alkyl, aryl or aryl-C.sub.1-3-alkyl, wherein the aryl or alkyl groups may be mono- or polysubstituted by halogen; while the term aryl groups used inthe definition of the above groups denotes phenyl or naphthyl groups, and X, Z, R.sup.1 to R.sup.5, R.sup.7a, R.sup.7b, and R.sup.7c have the meanings given in claim 1, and optionally cleaving said compound of any protective group of formula III, and/or,optionally selectively derivatizing at a hydroxy group or substituting a hydroxy group and/or, optionally resolving said compound obtained into its stereoisomers, and/or, optionally converting said compound into its a physiologically acceptable saltthereof.
23. A process according to claim 21, wherein at least one of R.sup.8a, R.sup.8b, and R.sup.8c is an alkylidene or arylalkylidene ketal or acetal group or two adjacent groups R.sup.8a, R.sup.8b, R.sup.8c, and R.sup.8d form a2,3-dimethyl-2,3-di(C.sub.1-3-alkoxy)-1,4-dioxane ring.
24. A process according to claim 22, wherein at least one of R.sup.8a, R.sup.8b, and R.sup.8c is an alkylidene or arylalkylidene ketal or acetal group or two adjacent groups R.sup.8a, R.sup.8b, R.sup.8c, and R.sup.8d form a2,3-dimethyl-2,3-di(C.sub.1-3-alkoxy)-1,4-dioxane ring. |
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